Diagnosis of Alzheimer's Disease

Rudolph C. Hatfield, PhD., edited by Kathryn Patricelli, MA

Imaging procedures to view the structure and function of the brain have improved dramatically since the early 2000s. However, doctors using these techniques alone are still unable to make an absolute diagnosis of Alzheimer's disease. The only way to really be sure that a person has Alzheimer's disease (to be 100% sure) is to take a biopsy (sample) of the person's brain tissue after they have died. This sample is then studied to see if there are plaques and tangles in the tissue. The approach to diagnosing Alzheimer's disease remains the same. The person is given a collection of tests to determine their diagnosis. Even though using this process does not result in the doctors and other medical staff being 100% sure that the person has Alzheimer's disease, the results of the tests are very accurate. Overall, using this process results in clinicians being over 90% sure that the diagnosis of Alzheimer's disease in any patient is the right diagnosis.

When Alzheimer's disease is suspected in someone the approach to diagnose the person's problems uses an interdisciplinary team of medical and mental health professionals that includes:

a geriatrician - a doctor who specializes in working with older people

a neurologist - a doctor who specializes in diseases of the nervous system

a psychologist - a doctor who specializes in mood and behavioral disorders

a neuropsychologist - a doctor who can perform testing to identify the nature and level of cognitive symptoms

a social worker - a social services professional who can link individuals and families to community services

other health professionals that can add important information to determine the diagnosis and needs of the person.

For the most part, this approach is only available in areas that have hospitals with large research facilities (most often these hospitals are attached to a university).

This complicated diagnostic process can be used to rule out any other possible conditions that could be creating the Alzheimer's-like symptoms in the person. These other conditions may be reversible or irreversible. An appropriate diagnosis is crucial to making treatment recommendations that are likely to be helpful. This is particularly important if the condition can be reversed. There are several parts of a diagnostic workup that often includes:

A full medical history - This includes questions about prior illnesses, previous injuries and surgeries, and current chronic conditions to identify other possible causes for Alzheimer's-like symptoms. For instance, a serious head injury - even from long ago - could account for problems with memory or concentration. A patient that has heart disease could have reduced blood flow to the brain, which is causing forgetfulness.

Medication history - This includes questions about allergies, side effects from past medications, and a list of current medications and dosages. Not only will this information help guide any future medication decisions, it also might reveal other information. For example, a medication interaction that is happening when two or more medications work against each other or compounding the effects of each other. The person could also be taking doses of medications that can produce confusion and other symptoms. Complete physical exam - This includes an assessment of hearing, vision, blood pressure, pulse, and other basic indicators of health and disease. A current physical exam can detect medical conditions such as an infection that might be causing confusion and other Alzheimer's-like symptoms.

Laboratory tests - This may include a collection of tests, depending on the person's medical history and current symptoms. For example, a blood glucose test might be ordered if the person is exhibiting symptoms of diabetes such as frequent urination, blurred vision, or increased thirst. Symptoms that came on suddenly and include severe confusion would suggest a urinalysis be done to rule out a urinary tract infection. Some scientists are currently refining a procedure that would allow a doctor to analyze a sample of cerebrospinal fluid, which is the fluid that surrounds and protects the brain and spinal cord. They hope that it will allow detection of the abnormal proteins that build up with Alzheimer's disease.

Neurological exam - This is a specific type of exam that is used to identify problems with the brain and nervous system. The evaluation should include an examination of the:

motor system (i.e., movement)

reflexes, gait (i.e., walking)

sensory functioning

coordination

This can help to detect nervous system problems that may be causing difficulties with thinking and behavior.